Conventional machines of this kind include a base on which is mounted a roller head carrier for a roller head, in particular a multi-roller head with, for example, three shaping rollers which are angularly spaced at 120.degree., a headstock which carries the tool for the workpiece to be shaped and a pressing tail spindle for a counter-holder which is associated with the workpiece held by the tool. The roller head carrier and the headstock are movable relative to one another for driving the shaping rollers along the workpiece with the help of a feed drive. One of the roller head carrier and headstock is connected fixedly to the base and the other is connected movably to the base.
In such conventional machines, the headstock and the unit which is formed by the roller head and the roller head carrier are mounted separately from one another and are spaced on the base. Thus, for carrying out the pressing or hydraulic pressing operation, for example the roller head carrier is moved toward the headstock with the help of the feed drive, the feed drive on its one side engaging the roller head carrier in the area of the base and on its other side engaging the base. In such an arrangement, a large tilting moment is applied to the roller head or the roller head carrier during the shaping operation, which tilting moment is determined by the shaping force, namely by the force which is applied by the headstock through the workpiece and the tool to the roller head, and by the vertical distance of the headstock axis from the headstock carrier guideway on the base. Said tilting moment, if large enough, can result in a tilting of the roller head carrier and a bending of the base and furthermore highly stresses the material of the roller head carrier.
Therefore the basic purpose of the present invention is to produce a machine of the above-mentioned type, in which the mentioned disadvantages are overcome, namely in which during the shaping operation tilting moments do not occur.
This purpose is attained inventively by the roller head carrier projecting from the side of the roller head facing the headstock and having a recess which extends in longitudinal direction of the machine. The headstock is arranged in such recess. The feed drive on its one side engages the headstock and on its other side engages the roller head carrier. The axes of the roller head, the headstock and the feed drive coincide.
The headstock and the roller head carrier are thus on the same side of the roller head and are arranged one in the other, wherein only center pulling forces and thus no tilting moments occur. In this manner the roller head carrier is not tilted and the base is not bent. Also, the guideway in the base, for the movable one of the headstock and roller head, is not loaded.
The roller head carrier has advantageously a framelike structure with two horizontal frame elements which are elongated in the longitudinal direction of the machine. The first of these frame elements faces the base and is supported on same. The second frame element is spaced from the first, wherein between the two frame elements there is arranged the headstock. The two frame elements can thereby be connected fixedly on their end facing the roller head through a vertical frame element which closes off the recess, wherein the feed drive on its one side engages the vertical frame element and on its other side, by penetrating through a hole in the vertical frame element, engages the headstock.
In order that the headstock is located in the recess during the maximum possible shaping, which occurs over the entire length of the tool, it is provided that the recess is longer than the headstock approximately by the length of the tool, such that in the initial position of the machine the roller head is spaced from the end of the tool facing the roller head.
The feed drive can be hydromechanical for achieving great precision and can contain a hydraulic motor, a gearing and a spindle, for example a ball roller spindle. However, it can also be formed, for example, by a hydraulic piston-cylinder-assembly, the cylinder of which is connected to the roller head carrier and the piston rod of which is connected to the headstock. Also an electric drive is possible.
In order to be able to connect the headstock to the base, the roller head carrier or its recess can be laterally open and the headstock, which is disposed in the recess, can be connected to the base through the lateral openings. It is thus advantageous that the headstock projects laterally beyond the roller head carrier and is connected fixedly to the base through cheek members, which extend around the first frame element of the roller head carrier. Such first frame element is guided slidably on the base, such that the roller head carrier is guided movably on the base. Thus in this case, upon operation of the feed drive, the roller head carrier is pulled past the headstock which is stationary on the base.
The two horizontal frame elements and the headstock can individually be platelike and of substantially rectangular cross section, which results in a strong construction at relatively small dimensions.
During the shaping operation the rollers apply a torsion moment onto the workpiece and through same onto the headstock. In order to absorb said torsion moment, it is possible to prevent relative rotation of the headstock and roller head carrier, for example with the help of a wedge guideway, wherein for example the headstock has a guide part on its upper side which faces the second frame part, which guide part engages a guide groove in the second frame element. If the other side of the headstock is fixedly connected to the base, one obtains through this a good absorption of the torsion moment in two areas which are on opposite sides of the axis of the headstock.